com.google.javascript.jscomp.js.es6.weakset.js Maven / Gradle / Ivy

/*
 * Copyright 2016 The Closure Compiler Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

'require es6/conformance';
'require es6/util/makeiterator';
'require util/polyfill';
'require es6/weakmap';

$jscomp.polyfill('WeakSet',
    /**
     * @param {*} NativeWeakSet
     * @return {*}
     * @suppress {reportUnknownTypes}
     */
    function(NativeWeakSet) {
  /**
   * Checks conformance of the existing WeakSet.
   * @return {boolean} True if the browser's implementation conforms.
   */
  function isConformant() {
    if (!NativeWeakSet || !Object.seal) return false;
    try {
      var x = Object.seal({});
      var y = Object.seal({});
      var set = new /** @type {function(new: WeakSet, !Array)} */ (
          NativeWeakSet)([x]);
      if (!set.has(x) || set.has(y)) return false;
      set.delete(x);
      set.add(y);
      return !set.has(x) && set.has(y);
    } catch (err) { // This should hopefully never happen, but let's be safe.
      return false;
    }
  }
  if ($jscomp.USE_PROXY_FOR_ES6_CONFORMANCE_CHECKS) {
    if (NativeWeakSet && $jscomp.ES6_CONFORMANCE) return NativeWeakSet;
  } else {
    if (isConformant()) return NativeWeakSet;
  }

  /**
   * @constructor
   * @extends {WeakSet}
   * @template TYPE
   * @param {!Iterator|!Array|null=} opt_iterable
   */
  var PolyfillWeakSet = function(opt_iterable) {
    /** @private @const {!WeakMap} */
    this.map_ = new WeakMap();

    if (opt_iterable) {
      var iter = $jscomp.makeIterator(opt_iterable);
      var entry;
      while (!(entry = iter.next()).done) {
        var item = entry.value;
        this.add(item);
      }
    }
  };

  /** @override */
  PolyfillWeakSet.prototype.add = function(elem) {
    this.map_.set(elem, true);
    return this;
  };

  /** @override */
  PolyfillWeakSet.prototype.has = function(elem) {
    return this.map_.has(elem);
  };

  /** @override */
  PolyfillWeakSet.prototype.delete = function(elem) {
    return this.map_.delete(elem);
  };

  return PolyfillWeakSet;
}, 'es6', 'es3');